Patent Document 1 discloses a touch-panel-equipped display device that includes an active matrix substrate on which pixel electrodes and reference lines are formed, a counter substrate on which counter electrodes that double as data signal lines are formed, and a liquid crystal layer interposed between the active matrix substrate and the counter substrate. In this touch-panel-equipped display device, signal potentials are applied to the data signal lines, whereby signal potentials are supplied through liquid crystal capacitors to the pixel electrodes, and mutual capacitors are formed between the pixel electrodes and the reference lines. When an object such as a finger touches the display surface of the active matrix substrate, charges of the reference lines fluctuate. By detecting the fluctuations of the charges of the reference lines, the touch position is detected.